Inorganic-aptamer hybrids for live cell imaging

With this award, the Chemistry of Life Processes Program in the Chemistry Division is funding Dr. Edith Glazer from the University of Kentucky to develop a short RNA sequence, called an aptamer, that can be observed to go through its life cycle in a cell using fluorescence microscopy. RNA has the task of translating the genetic information that is stored in DNA to create the proteins that serve as the workhorses in the cells of all living organisms. By observing how the amount of RNA changes in a cell, scientists can study how this flow of information is controlled in a time-dependent manner. The Systematic Evolution of Ligands by Exponential Enrichment (SELEX) method is used to evolve RNA aptamers that bind to a small molecule containing a ruthenium (Ru) metal ion. This inorganic compound is designed to light up when it binds to form a complex with its specific RNA partner, as the two fit together in lock and key fashion. The light emitted by the complex is visualized by fluorescence microscopy and other optical methods to “see” the RNA aptamer as it is being produced and later degraded. The research project provides training to undergraduate and graduate students in organic and inorganic synthesis, molecular biology, and various light microscopy techniques. The project will also be integrated into an educational program aimed at increasing retention and success rates in chemistry for students that are women and members of underrepresented groups. The ability to accurately track and quantify RNA levels or localization, either on the subcellular or tissue levels, is important to the understanding of the role of RNA in the regulation of biological processes. This research project develops new emissive ruthenium (Ru(II)) compounds for tracking RNA in live cells through the creation of optimized pairs of luminescent compounds and RNA aptamers. The Ru(II) compounds do not suffer from photobleaching or excited state conformational changes, overcoming a key obstacle in the field of optical RNA reporters. The research increases the understanding of how synthetic modification alters excited state energies and relaxation pathways in luminescent Ru(II) complexes, and how specific modifications determine RNA selectivity. Systematic Evolution of Ligands by Exponential Enrichment (SELEX) is a powerful method to develop nucleic acids that bind target small molecules, and the combination of SELEX with modular chemical modification of the Ru(II) complex provides optimized binding partners. This project combines the techniques of synthetic chemistry, molecular biology, and microscopy to develop new tools to improve the understanding of RNA biology. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.